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Dryad

Monitoring of insecticide resistance and transcriptomic analysis of detoxification gene expression in field populations of Asian citrus psyllid, Diaphorina citri Kuwayama, in China

Abstract

Diaphorina citri is one of the most destructive pests to global citrus production. Chemical control through insecticide application has traditionally served as the primary intervention strategy for suppressing D. citri populations. However, recent field observations indicated diminishing efficacy of several commonly insecticides against this pest, suggesting potential resistance development. This investigation aims to evaluate insecticide resistance profiles in D. citri populations collected from various Chinese citrus-growing provinces and to elucidate the underlying molecular mechanisms. This study revealed variable insecticide resistance profiles across ten field populations of D. citri. The Ganxian population displayed low to moderate resistance to thiamethoxam (RR₅₀=5.52), imidacloprid (RR₅₀=7.39), and chlorpyrifos (RR₅₀=10.70), while the Nanfeng population remained largely susceptible to most insecticides, exhibiting only very low chlorpyrifos resistance (RR₅₀=2.34). Chlorpyrifos resistance was most pronounced in the Huichang population (RR₅₀=15.93). Nine field populations showed very low to low resistance to thiamethoxam and imidacloprid, while all populations demonstrated minimal resistance to dinotefuran, clothianidin, and lambda-cyhalothrin. Transcriptomic analysis revealed significant enrichment of differentially expressed genes in the resistant Ganxian population related to xenobiotic metabolism pathways. Notably, 19 cytochrome P450 genes, three glutathione S-transferase genes, and one UDP-glycosyltransferase gene were significantly overexpressed compared to the susceptible Nanfeng population. Field populations of D. citri across the citrus-growing regions of China have developed varying levels of resistance to organophosphates, pyrethroids, and neonicotinoids, with enhanced metabolic detoxification mechanisms playing a significant role in resistance development. These findings provide crucial insights for developing effective insecticide resistance management strategies to sustain chemical control efficacy against D. citri.